TV-Series
Description
Issei Ryudou is a supporting character in Fate/stay night, best known as the diligent student council president of Homurahara Academy and the closest friend of the protagonist, Shirou Emiya. He is a second-year student in Class 2-C, standing at 170 centimeters tall, with a lean build and a preference for austere, traditional values. He is the younger son of the head priest of Ryudou Temple, a Buddhist temple in Fuyuki City, and lives there with his family. His daily commute to school is a rigorous two-hour walk, a discipline that contributes to his notable physical endurance.

In terms of personality, Issei is defined by his serious, straight-laced, and principled nature. He is an exemplary student who dislikes frivolity and fashionable trends, often coming across as stern, particularly during his duties as student council president. Despite this rigid exterior, he is not inflexible; he treats most people with courtesy and is capable of making reasonable exceptions. His most defining personal trait is his fraught relationship with his classmate, Rin Tohsaka. The two served together on the middle school student council, with Issei as president and Rin as vice-president, a period that left him with a deep-seated distrust of her. He frequently refers to her as a "vixen" or "witch," believing she is duplicitous and manipulative. However, this enmity does not translate into a blanket fear of all women. He immediately warms up to Saber, sensing her inherent goodness, and holds the honest and direct Ayako Mitsuzuri in high regard. His preference for meat dishes, which he actively seeks out from the bento lunches Shirou makes for him, is a notable quirk, stemming from the predominantly vegetarian diet of the temple.

Issei's motivations are grounded in his ordinary human life, which serves as a stark contrast to the magical conflict of the Holy Grail War. As the son of a temple priest, he is destined to enter the monkhood after graduation. This upbringing has instilled in him a strong sense of duty and discipline, which he channels into his role as student council president. He is passionate about reforming school policies, particularly the unfair distribution of funds to sports clubs, though his efforts often meet resistance. He is not a magus and has no magical abilities, remaining a normal human throughout the story. His primary motivation is to live an honorable life and maintain the integrity of his school and family name, inspired by his accomplished elder brother, Reikan.

Within the narrative of Fate/stay night, Issei serves as an anchor to Shirou's everyday life. He is a confidant who provides a sense of normalcy, often asking Shirou to use his repair skills to fix broken school equipment to save on costs. His role in the Holy Grail War is almost entirely passive and circumstantial. Because Caster uses Ryudou Temple as her base of operations, Issei becomes a suspect in Rin's eyes as a potential Master. In one instance, Shirou is forced to strip Issei to check for Command Spells, a scene played for awkward humor. Living under the same roof as the Servant Caster and her Master, Souichirou Kuzuki, puts him in danger without his knowledge. Depending on the story route, he is either placed under a hypnotic suggestion by Caster or rendered unconscious during the battles that take place at the temple.

His key relationships define his role in the story. His friendship with Shirou Emiya is his most important bond; he trusts Shirou completely and relies on him for both practical help and moral support, even joking that he wishes Shirou were his underclassman so he could pass on the presidency to him. He holds his homeroom teacher and Shirou's guardian, Taiga Fujimura, in some regard as a family acquaintance. His relationship with his mentor, Souichirou Kuzuki, is one of deep respect; he looks up to the stoic teacher as an older brother and occasionally practices kata with him. Conversely, his dynamic with Rin Tohsaka is one of open hostility, though it borders on a grudging rivalry where he still acknowledges her capabilities as a human being.

While Issei does not undergo a dramatic character arc, his development is seen in his interactions with the supernatural. He remains a consistent figure of integrity, and his ability to perceive character—instantly trusting Saber while distrusting Rin—is proven accurate. Notably, he survives the events of the Holy Grail War largely unscathed, a rare outcome for a normal civilian caught at the edge of a magical conflict.

Regarding his notable abilities, Issei is entirely non-magical and has admitted his ability to sense the supernatural is weak. However, he possesses exceptional mundane skills. He is a skilled karate practitioner who has earned a black belt, and he would have joined the karate club if not for his student council duties. He is also adept at analytical thinking, demonstrated by his skill in games like go and crossword puzzles. His leadership and administrative abilities are so effective that his peers find him irreplaceable, making it difficult to find a successor for his council position.